I'm looking over an approximately 600 page PDF file, stored on my local machine. I'm using OS X Preview app to view it.

There is significant delay when scrolling the page, and also doing text searches. I'm surprised because I didn't think the code involved with scrolling a PDF document and performing searches would be very computationally expensive.

I would try another app first. I don't own a mac, but it could be one of the two following problems:

1. The app is only opening one page at a time, and fetching each page fresh from the hard drive. It may detect that the 600 pages is too big to deal with in one go, which might be causing this scrolling delay. Another app might handle the scrolling better, like loading a thumbnail for each page and using that to represent scrolling, loading only the final page you land on.

2. The PDF you are using might not have text in it if it was a scan. The app could be trying to do real time OCR on the image as it loads each page. Another app might do this differently.

Xanthir wrote:I find that universally, PDF readers are terrible for no good reason. A perfectly equivalent web page would scroll/etc vastly better. Very annoying when trying to, say, use a D&D pdf to play from. :/

Pretty much this. Outside of SumatraPDF (lightweight and pleasant) and mupdf (supremely bare-bones but no-bullshit) every PDF reader I've encountered has been awful. Of course, Acrobat (sorry, sorry, Adobe) Reader itself is King of Trash Mountain in that contest, but there's plenty of other worthy contenders.

"'Legacy code' often differs from its suggested alternative by actually working and scaling." - Bjarne Stroustrupwww.commodorejohn.com - in case you were wondering, which you probably weren't.